Cattaneo, Z. 1 & Vecchi, T. 2
1 Department of Psychology, University of Milan-Bicocca, Italy
2 Department of Psychology, University of Pavia, Italy
Individuals typically show a leftward bias - known as pseudoneglect - in bisecting physical lines as well as numerical intervals. We found that congenitally blind individuals show such leftward bias in haptic as well as in numerical bisection (thus reflecting the spatial nature in which numbers are represented, the mental number line). These findings support the view that pseudoneglect operates at a mental representational level rather than being perceptually-based. Moreover, the consistent leftward bias shown by blind individuals in both line and numerical bisection suggests that the right hemisphere dominance in spatial processing, resulting in an overestimation of the left side of space, develops even in the absence of any visual input. Further, monocular and strabismic individuals were also tested and the pattern of performance was less consistent suggesting that an imbalance between the inputs from the two eyes may have a different impact compared to blindness on the development of attentional spatial mechanisms.